Alkali metal or alkaline earth metal salts of polycarboxylic acids have been used in polyester polymers to increase the crystallinity or the rate of crystallization.
U.S. Pat. No. 3,761,450 describes molding compositions based on linear saturated polyesters comprising small amounts of lithium and/or sodium salts of polycarboxylic acids to bring about a high crystallinity in the heated mold after a short time. Polyesters and salts of polycarboxylic acids are disclosed generally. Poly(ethylene terephthalate) and disodium 1,10-dodecanedicarboxylate are exemplified.
U.S. Pat. No. 5,264,477 discloses an improved melt processable liquid crystalline polyester composition capable of forming an anisotropic melt phase and having an improved heat distortion temperature under a load by using 0.05 to 1.0 weight percent of a divalent metal salt of an aromatic dicarboxylic acid, wherein the metal is zinc, calcium, cadmium, barium or mixtures thereof.
U.S. Pat. No. 4,380,621 discloses fast crystallizing polyesters in which at least some of the acid end groups of the polyester have the formula --COO.sup.- M.sup.+ where M.sup.+ is an alkaline metal ion. Poly(ethylene terephthalate) and poly(butylene terephthalate) are specifically disclosed. Poly(ethylene terephthalate) is exemplified. Sodium containing species exemplified include sodium hydroxide, sodium benzoate and sodium o-chlorobenzoate.